Such a device is described in U.K. Pat. No. 1,062,701. This device has walls defining a settling chamber having an inlet opening and an outlet opening in its upper region. Means are provided for connecting the chamber in series with the liquid supply line. A float is located in the chamber and has a specific gravity higher than that of the supply liquid and lower than that of the foreign liquids. Electrical switch means having means for connection to an electrical warning signal are operable by the float so that when the float is in an upper position the circuit is closed and when the float is in a lower position the circuit is open. A warning signal is thus produced when the upper surface of the foreign liquids trapped in the settling chamber reaches a predetermined level.
A foraminous element is provided in the settling chamber and arranged in such a way that liquid flowing from the inlet opening to the outlet opening will pass at least once through the foraminous element.
A drain outlet valve is provided for the lower region of the settling chamber to permit foreign liquids which are separated out and trapped in the settling chamber to be drained from the chamber.
An improved device shown in U.S. Pat. No. 4,010,101 comprises a tubular side wall having upper and lower ends, upper and lower end pieces defining sockets releasably receiving the upper and lower ends of the side wall, and sealing means forming seals between the end pieces and the side wall, a settling chamber being defined primarily by the side wall and the end pieces. Inlet and outlet chambers are provided in the settling chamber and adjacent to said upper end piece, an inlet leading through the upper end piece into said inlet chamber and an outlet leading through the upper end piece from the outlet chamber. A substantially imperforate wall separates the inlet and outlet chambers. The imperforate wall is an improved wall comprising a tubular hub and a pair of wing means at opposite sides of the hub. These wing means each diverge outwardly away from the hub and serve to increase circulation of supply fluid flowing through the device.
Flow paths connect said settling chamber with said inlet and outlet chambers and foraminous wall means are arranged across the flow paths whereby fluid passing through the chambers from the inlet to the outlet passes through the foraminous wall means.
The foraminous wall means each form part of a substantially cylindrical wall so that an annular cavity is defined about this wall. The wing means can cause circulation of supply fluid through this cavity and through the foraminous wall means to increase the efficiency of the wall means.